ABSTRACT Background: Errors in RT are estimated to occur in up to ? 5% of the > ?600,000 patients receiving RT per year in the US; with serious/lethal events occurring ? 1 of 1,000-10,000 patents. Radiation therapy technicians (RTTs) are responsible for delivering very high doses of radiation according to the prescribed plan. Flaws in workflows (e.g. understaffing), suboptimal physical workspace design (e.g. congested workspaces) and environmental stressors (e.g. interruptions) negatively affect RTTs performance thus compromising patient safety. Aim: To assess the impact of modifications to workflows, workspace design, and environment factors on RTTs? workload (WL), situation awareness (SA), and performance during pre-treatment QA tasks in simulated environment. Method: WL (mental and physical) and SA will be assessed subjectively and objectively using various validated tools and performance will be assessed subjectively using a self-assessment and objectively using quantification of errors (# of errors made) and severity of errors.